# The Order Book

Because AlphaDex provides the back-end DEX functionality for many front-end exchanges (like ShardSpace) the order book you see shows all the orders existing on AlphaDex and not just those submitted on ShardSpace. When you place either a buy order (in green) below the market 'Price' or a sell order (in red) above the market 'Price' it will get added to the order book. If you submit a buy order above the market price or sell order below the market price these are normally executed asap and are usually not added to the order book. Liquidity depending.

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